An electromagnetic actuator 100 (FIG. 1) for a valve 110 comprises mechanical means, such as springs 102 and 104, and electromagnetic means, such as electromagnets 106 and 108, for controlling the position of the valve 110 by means of electric signals.
The stem of the valve 110 is applied for this purpose against the rod 112 of a magnetic plate 114 located between the two electromagnets 106 and 108.
When a current is flowing in the coil 109 of the electromagnet 108, the latter is activated and generates a magnetic field attracting the plate 114, which will come into contact with it.
The simultaneous displacement of the rod 112 permits the spring 102 to bring the valve 110 into the closed position, the head of the valve 110 coming against its seat 111 and preventing the exchanges of gas between the interior and the exterior of the cylinder 117.
Analogously (not shown), when a current is flowing in the coil 107 of the electromagnet 106, the electromagnet 108 being deactivated, it will be activated and attracts the plate 114, which will come into contact with it and displace the rod 112 by means of the spring 104 such that the rod 112 acts on the valve 110 and brings the latter into the open position, the head of the valve being moved away from its seat 111 to permit, for example, the admission or the injection of gas into the cylinder 117.
Thus, the valve 110 alternates between the open and closed positions, the so-called commuted positions, with transient displacements between these two positions. The state of an open or closed valve will hereinafter be called the “commuted state.”
The actuator 100 may also be equipped with a magnet 118 located in the electromagnet 108 and with a magnet 116 located in the electromagnet 106, which said magnets are intended to reduce the energy needed to maintain the plate 114 in a commuted position.
Each magnet is located for this purpose between two subunits of the electromagnet with which it is associated in such a way that its magnetic field, possibly combined with the field generated by the electromagnet, reinforces the maintenance of the valve 110 in the open or closed position. For example, the magnet 116 is located between two subunits 106a and 106b.
Due to the action of the magnet on the magnetic plate, such an electromagnet 106 or 108, called an electromagnet with a magnet or a polarized electromagnet, requires considerably less energy to control a valve, the maintenance of a valve in a commuted position representing a considerable energy consumption for the actuator.